Identification of MPK4 kinase interactome using TurboID proximity labeling proteomics in Arabidopsis thaliana.

TurboID is a new and efficient proximity labeling system that was first developed in living mammalian cells. TurboID is a modified bacterial biotin ligase that can be fused to a bait protein, which can then modify proximal interacting proteins with biotin. Prey proteins subsequently labeled with biotin tags will be pulled down with streptavidin-coated beads and identified by mass spectrometry-based proteomics. TurboID has been recently applied to living plant cells and provided promising results in identification of interacting proteins. Mitogen-activated protein kinase 4 (MPK4) is important for plant growth, development, and defense; however, the molecular mechanisms underlying the range of MPK4 functions are not completely known. Here we use modern proteomics together with the TurboID in a proof-of-concept study to profile the MPK4 interactome and uncover the functions of MPK4 in plant signaling cascades.